BBC News interviews Prof Sarah Harper on her recent Royal Society Report 'People and the Planet'.
'According to the UN the world population is set to rise to 10 billion before the end of the century, while dramatic shifts in the distribution, age composition and mobility of all those extra people will twist the kaleidoscope of the global population challenge.
Most of the growth - some two billion - will come in Africa, where fertility rates remain high. But according to Professor Sarah Harper, co-author of the report, we're also getting older, migrating to cities, and increasing our levels of consumption as developing nations like China close the gap on the west.'
> BBC News article 'Planning to flourish in a world of seven billion'
